SUBFEST 2011-HuskerOmaha and Desertdome's Subwoofer Showdown - Page 9 - AVS Forum
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Old 10-27-2011, 03:41 PM
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Originally Posted by Mark Seaton View Post

That might be cherry picking comments and a bit out of context. Given more exposure and comparisons, when there isn't any trade off in output capability by using plenty of subs, I have yet to see a case where someone says, "Please cut off that deep extension for me!" Harman has done the most study on such things, and the general trend is as bosso suggests, but even holding to a +/-3dB window you can make a system sound dramatically different below ~100Hz.

What I was referring to was largely a matter of what strengths and especially weaknesses will be most obvious to one listener vs. another. IMO the ownership biases come more into play with the written defense of the ratings after the fact here and not while making the rankings.


My post was agreeing with yours about individual preference and taste and their importance in audio rather than advocating cutting off extension.

With nothing to loose by all means the extension is a nice to have but there is usually a trade off in output. This is because people always have constraints in terms of money,space and so forth. One must prioritize.

LTD02, Thanks for the links! Looks like some nice reading.

bosso, will read up on that. Yes I was looking for "X reputed company/person tested it on X people". The reason I am not looking into the GTG results is because it addresses an informal sub comparison with the subs EQed to the same curve. It does not attempt to identify the preferred frequency curve of the attendees.
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Old 10-27-2011, 03:53 PM
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Originally Posted by J_Palmer_Cass View Post

The fly in the ointment is that for the vast majority of the population that tradeoff is required.

No disagreement there. That's something I'm very aware of and conscious of when designing subs and the reason that the behavior of subwoofers as they approach their higher output levels (or even exceed them) matters so much.

It's also easy to forget here how significant the anechoic response can affect the impressions and what is achieved in someone's own system vs. what might be possible with the right bit of EQ.

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Old 10-27-2011, 03:57 PM
 
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Originally Posted by J_Palmer_Cass View Post

When you move from the 80 phon curve to the 100 phone curve, the numbers show that the 20 dB difference at 1 kHz equates to the 8 dB difference at 20 Hz.

OK, but you referenced the FM curve originally, not the ELC.

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Originally Posted by Decadent_Spectre View Post

The reason I am not looking into the GTG results is because it addresses an informal sub comparison with the subs EQed to the same curve. It does not attempt to identify the preferred frequency curve of the attendees.

They weren't EQ'd indentically, the Submersive extended an octave lower. Completely coincidentally it was also most preferred...
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Old 10-27-2011, 04:04 PM
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Originally Posted by BiGBADDABOOM View Post

OK, but you referenced the FM curve originally, not the ELC.

JPC is right here. The 10dB for subjective doubling of loudness is referenced to 1kHz. As you get to lower frequencies, the spacing between the curves reduces and even changes with level to a degree. Once over the hearing threshold, it doesn't take as much below 20Hz as it does at 1kHz to sound much louder. An example would be that 60-70phon probably only takes about a 6dB increase at 20Hz rather than 10dB. My own and other's casual experiments and observations have aligned well with this, where a 1-3dB shelf below 20-25Hz, once loud enough, can be much more audible than expected based on the same shelving changes above 1kHz.

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Old 10-27-2011, 04:13 PM
 
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Thanks, I've got it now after seeing that last graph. Initially he referenced the Fletcher–Munson curve and this is what I see:



At 100dB down low it actually looks like it's expanding over 1KHz.
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Old 10-27-2011, 04:18 PM
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Originally Posted by BiGBADDABOOM View Post

OK, but you referenced the FM curve originally, not the ELC.



No big deal one way or the other. I must be getting old!


"Until recently, it was common to see the term 'Fletcher–Munson' used to refer to equal-loudness contours generally, even though a re-determination was carried out by Robinson and Dadson in 1956 , which became the basis for an ISO 226 standard.

It is now better to use the generic term "Equal-loudness contours", especially as a recent survey by ISO redefined the curves in a new standard, ISO 226:2003"



http://en.wikipedia.org/wiki/Fletche...3Munson_curves
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Old 10-27-2011, 04:21 PM
 
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"It is now better to use the generic term "Equal-loudness contours", especially as a recent survey by ISO redefined the curves in a new standard, ISO 226:2003""
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Old 10-27-2011, 04:34 PM
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Originally Posted by BiGBADDABOOM View Post

They weren't EQ'd indentically, the Submersive extended an octave lower. Completely coincidentally it was also most preferred...

There are many confounding factors. I think people are overlooking that. This is not controlled so the most we can make of this is wonder why something happened to develop a hypothesis.

The BHD is composed primarily of subsonic content. I thought the feeling was subtle. It would most likely be better with more displacement though. If this content was present in other clips, it would probably make a subtle change. The Submersive was also the most preferred on the Kid Cudi song (intense pressurization). However it might of been at a slightly louder playback volume. The Kid Cudi song only plays down to 40 Hz but we felt the impact of this.

I have other questions such as:

If we can feel the 40 Hz content greater then the under 20 Hz content in this scenario, would a sub pushed harder producing lets say second order distortion 10dB down from the fundamental increase the pressurization also?

If a sub seems to last longer in the time domain, does the listener feel more pressurization since the frequencies are present longer?

I felt the chairs shaking many scenes. Does the listener associate the resonating of the chair as pressurization?

Wish I was still in the EE program, I could of got funding to maybe actually conduct a controlled study useful to many . It would provide a start but multiple trials would still need to be conducted.

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Old 10-27-2011, 04:37 PM
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Quote:
Originally Posted by Mark Seaton View Post

That might be cherry picking comments and a bit out of context. Given more exposure and comparisons, when there isn't any trade off in output capability by using plenty of subs, I have yet to see a case where someone says, "Please cut off that deep extension for me!" Harman has done the most study on such things, and the general trend is as bosso suggests, but even holding to a +/-3dB window you can make a system sound dramatically different below ~100Hz.

Quote:
Originally Posted by J_Palmer_Cass View Post

The fly in the ointment is that for the vast majority of the population that tradeoff is required.

The vast majority of the population aren't members here. I've always felt this to be a lame argument. When I first set out to design a subwoofer system, the last thought in my head would have been "Hmmmm, how do I factor in what the vast majority does?".

Folks who start threads looking for 'the best sub for under $200' (probably a majority of the sub-buying population, but certainly not the 'vast' majority, who don't own a subwoofer at all) don't hijack threads about the SubMersive to tell everyone that they don't "want" or "care about" anything below 30 Hz.

No, it's the folks who just bought into the latest multi-sub-gizmo-setup fad or uber-ID-darling, both of which have just so happen to have no output below 20 Hz, who do just that.

In this forum, it's far more about that bias thing than it ever will be about the state of the art. State of the art is what it is, It's not subject to Democracy.

Bosso
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Old 10-27-2011, 05:38 PM
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Originally Posted by bossobass View Post

The vast majority of the population aren't members here. Bosso


But there are 987,653 members registered here. What percent of the 987,653 members who are registered here have bass capability down to 3 Hz at reference level when measaured at the LP?
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Old 10-27-2011, 05:42 PM
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Originally Posted by J_Palmer_Cass View Post

But there are 987,653 members registered here. What percent of the 987,653 members who are registered here have bass capability down to 3 Hz at reference level when measaured at the LP?

Better yet, how many of them would want it if they could? Which they can.

My Dual 18" LLT subs 120dB down to 10hz

 

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Old 10-27-2011, 05:57 PM
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Weeeeellllll....

People want their deep bass, man! The power's to be need to provide it to the people.

My Dual 18" LLT subs 120dB down to 10hz

 

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Old 10-27-2011, 06:08 PM
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Originally Posted by Scott Simonian View Post

Weeeeellllll....

People want their deep bass, man! The power's to be need to provide it to the people.


I have no objection to deep bass at loud SPL levels. Just can't fit the equipment into my room, so I have to compromise a bit!

That being said, you don't need deep extension to watch television programming or to playback most music.

Most of the 1000 DVD's that I own are pre 1980 movies, so no need for deep bass (sub 20 Hz area) playback capability to playback most of those movies either.

After taking into consideration the content on a lot of the present day "bombastic" movies, I am not sure if I need to go much deeper than 20 Hz at high levels anyhow. If the movie is a dog, who cares if the bass extension is great!
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Old 10-27-2011, 06:40 PM
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Originally Posted by J_Palmer_Cass View Post


Most of the 1000 DVD's that I own are pre 1980 movies...

Really? I have to see this collection.

Panasonic P60ST50-Yamaha RX-V467 receiver-Sony PS3-Velodyne SMS-1-Canton 430 mains, 455 center and 402 surrounds-Rythmik FV15HP subwoofer- Pro-ject Debut III turntable- I also have a pair of Mark K's DIY design, the ER18DXT's
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My humble entertainment room
http://www.avsforum.com/t/1417652/midwest...
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Old 10-27-2011, 08:18 PM
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Originally Posted by kwarny View Post

There are many confounding factors. I think people are overlooking that. This is not controlled so the most we can make of this is wonder why something happened to develop a hypothesis.

The BHD is composed primarily of subsonic content. I thought the feeling was subtle. It would most likely be better with more displacement though. If this content was present in other clips, it would probably make a subtle change. The Submersive was also the most preferred on the Kid Cudi song (intense pressurization). However it might of been at a slightly louder playback volume. The Kid Cudi song only plays down to 40 Hz but we felt the impact of this.

I have other questions such as:

If we can feel the 40 Hz content greater then the under 20 Hz content in this scenario, would a sub pushed harder producing lets say second order distortion 10dB down from the fundamental increase the pressurization also?

If a sub seems to last longer in the time domain, does the listener feel more pressurization since the frequencies are present longer?

I felt the chairs shaking many scenes. Does the listener associate the resonating of the chair as pressurization?

Wish I was still in the EE program, I could of got funding to maybe actually conduct a controlled study useful to many . It would provide a start but multiple trials would still need to be conducted.

Hi Kwarny,

I read your write up with a lot of interest. Great job, and thanks for that.

I was most interested in your comments because your sub had an equally flat response to 10 Hz (unfortunately, the bottom of the graph), that being the only other sub in the group besides the SM with that distinction.

Being that the SM has dual 15s and around +8dB more juice, I believe that made a significant difference in the presentation. Since SPL can easily be equalized by multiples, there should be little difference if that were the case, IMO. It would be interesting to hear about such a comparison some day using multiples of Rythmiks to get to a specific playback level.

The sub that produces ULF at reference level doesn't seem to be lasting longer... it is lasting longer.

It's simple physics. A 30 Hz sound wave (33.3 ms) decays 6 times faster than a 5 Hz sound wave (200 ms). Therefore, wherever the FR of a sub may be arbitrarily rolled off, either by design or by the limitations of its alignment, is the biggest contributor to sonic signature with playback of full BW source.

Ringing is a different phenomenon and should be fairly easily differentiated from ULF decay times because it occurs in an audible range of frequencies.

Here's a SL comparison of my sub mic'd at the listening position vs the digital feed from the player of the lightning strikes in WOTW. You can see that it's a very good reproduction of the ones and zeroes, but notice that the mic'd version decays much slower than the digital version (at the far left, lowest frequencies):


I wasn't awrae of the phenomenon until I looked closely at these graphs, otherwise I would have noted the scroll speed and the time interval to match them up against 4 Hz, and some day I will actually do this more scientifically.

With ULF (say below 15 Hz), the chair (or whatever else in the room) doesn't resonate. A chairs resonant frequency is well above 20 Hz. Contrary to the vernacular, subwoofers don't "move air". They send a pressure wave outward using the air as a medium. The air molecules compress and then expand as the wave moves through it. If this pressure wave is strong enough, it can cause the walls, floor, chair, etc., to 'move' in reaction to the pressure wave. This can definitely be felt and is different from the same effect caused by a much higher frequency (say 40 Hz) sound wave. 'Vibration' is probably a better word to describe the effect of a higher frequency effect, added to the fact that the higher frequency effect is audible and the ULF is not.

I agree that BHD is less effective. That's because it's ULF (6 Hz and 18 Hz) are a constant tone. What many new sound designers seem to have discovered is that ULF is much more effective in pulses and bursts. Star Trek uses this effect very effectively and the pulses and the subsequent room reaction are unmistakably present, whereas the constant drone of a ULF frequency is a completely, and as you put it, more subtle effect.

Star Trek; Romulun ship emerges from the black hole in Ch 1:


Another thing to consider is that, like BHD, a lot of designers use naturally occurring sounds (like the chopper blades in BHD) or create sounds that have multiple tones, a la harmonic distortion. BHD is comprised of 6 Hz, 3HD (18 Hz), 5HD (30 Hz), etc... So, with many of them, it's impossible to notice harmonic distortion because it's masked by the tones of the effect.

If a sub produces harmonics that are still in the <20 Hz range (for example, a 5 Hz burst would have 2HD of 10 Hz and 3HD of 15 Hz, all inaudible), then yes, it would actually add to the effect, although when you are talking about tones that are below hearing, 10% or so is not that significant. So, no I don't think it makes a lot of difference unless the sub is producing very high harmonic distortion in the first 2 octaves.

Just thought you might be interested in some of this stuff, and wanted to thank you for your input.

Bosso
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Old 10-27-2011, 09:29 PM - Thread Starter
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Another thing I forgot to mention in my write up that I'm just remembering: the CHT SS 18.2 had the drivers facing the wall and the room while the submersive had the drivers facing the center and rack.

I'm wondering what kind of difference that alignment made so when desertdome comes over to get his stuff we can take one of the dual opposed mfw down and test it out. We can do the same pre and post EQ in both situations and post those. Or is that a waste of time?
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Old 10-27-2011, 09:44 PM
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in my theater room, i have the sub the way we had it set up in your basement, one facing the LP, one facing the wall. About a foot from the rear wall, and 2 feet from the left wall.
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Old 10-27-2011, 11:54 PM
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Quote:
Originally Posted by bossobass View Post

Hi Kwarny,

I read your write up with a lot of interest. Great job, and thanks for that.

I was most interested in your comments because your sub had an equally flat response to 10 Hz (unfortunately, the bottom of the graph), that being the only other sub in the group besides the SM with that distinction.

Being that the SM has dual 15s and around +8dB more juice, I believe that made a significant difference in the presentation. Since SPL can easily be equalized by multiples, there should be little difference if that were the case, IMO. It would be interesting to hear about such a comparison some day using multiples of Rythmiks to get to a specific playback level.

kwarny - Hi Bosso. I am glad you responded cause if no one does then either I am a lunatic without even trying or I am completely right and everyone agrees which I know is not true . I agree. I mentioned to HuskerOmaha that I wanted to build three more kits and run them in separate boxes but use a push/pull orientation so I would have duals similar to his dual 18.1s. We might be able to get duals and mine (3 total) together hopefully soon back up in Omaha's theater.

The sub that produces ULF at reference level doesn't seem to be lasting longer... it is lasting longer.

It's simple physics. A 30 Hz sound wave (33.3 ms) decays 6 times faster than a 5 Hz sound wave (200 ms). Therefore, wherever the FR of a sub may be arbitrarily rolled off, either by design or by the limitations of its alignment, is the biggest contributor to sonic signature with playback of full BW source.

Ringing is a different phenomenon and should be fairly easily differentiated from ULF decay times because it occurs in an audible range of frequencies.

kwarny - Agreed about the physics also. Covered this a little in my elementary physics course last year. It is also apparent on water fall charts when used to measure room response. I considered this but the low bass should mostly be felt, not heard I believe. I heard the excess of (need to learn the vocabulary) notes during every clip throughout it including music. Looking from the graphs of the clips, many did not go below 30 Hz and it's not like the bass is constant throughout the whole clip. I assume the Rythmik was not power compressing the whole time .

It sounds like I need to find the proper words or lack of words. I will use articulate referring to the time domain and tone or timbre referring to the sound of the note. I thought the CHT SS 18.2 was more articulate and had a better timbre than the eD. The CHT was however played at a louder volume so I noticed greater impact which is enjoyable.

Different scenario. We are more sensitive in the higher frequencies so maybe this is only due to distortion or frequency response. When I auditioned the Song Tower Dome and the HT2 with the LCY ribbon, there was a noticeable difference. I was expecting an added sizzle in the highs because of what Jim and Dennis mentioned comparing the LCY and RAAL tweeter. To my surprise, the LCY sounded more transparent than the dome OW2. It was as if there was not a tweeter there and I ended up loving the sound. Maybe due to the quick CSD of the ribbon. I have never heard a tweeter to disappear like this before, even in Joseph Audio's model that uses an exel midrange but with a silk dome tweeter.



Here's a SL comparison of my sub mic'd at the listening position vs the digital feed from the player of the lightning strikes in WOTW. You can see that it's a very good reproduction of the ones and zeroes, but notice that the mic'd version decays much slower than the digital version (at the far left, lowest frequencies):


I wasn't awrae of the phenomenon until I looked closely at these graphs, otherwise I would have noted the scroll speed and the time interval to match them up against 4 Hz, and some day I will actually do this more scientifically.

kwarny - Agreed also .

With ULF (say below 15 Hz), the chair (or whatever else in the room) doesn't resonate. A chairs resonant frequency is well above 20 Hz. Contrary to the vernacular, subwoofers don't "move air". They send a pressure wave outward using the air as a medium. The air molecules compress and then expand as the wave moves through it. If this pressure wave is strong enough, it can cause the walls, floor, chair, etc., to 'move' in reaction to the pressure wave. This can definitely be felt and is different from the same effect caused by a much higher frequency (say 40 Hz) sound wave. 'Vibration' is probably a better word to describe the effect of a higher frequency effect, added to the fact that the higher frequency effect is audible and the ULF is not.

kwarny - Agreed again . Sound waves are longitudinal. I remember when you linked the video of a sub with smoke? in the room and you could see that occurring. Much more interesting then trying to simulate it with a long spring.

I was vague about the chairs. I could feel the chair vibrate during many scenes including the Kid Cudi track with the lowest note around 40 Hz. I was thinking, if the chair resonated at 60 Hz (made up value) and it was easily felt with 95 dB, then maybe if the fundamental was 30 Hz at 105 dB that the 2nd order at 60 Hz with 10% distortion (around 95 dB) that the chair would be felt too which people may perceive as impact. It is just something I thought of last weekend. Be fun to see a study where the seating was swapped between listening.


I agree that BHD is less effective. That's because it's ULF (6 Hz and 18 Hz) are a constant tone. What many new sound designers seem to have discovered is that ULF is much more effective in pulses and bursts. Star Trek uses this effect very effectively and the pulses and the subsequent room reaction are unmistakably present, whereas the constant drone of a ULF frequency is a completely, and as you put it, more subtle effect.

kwarny - It sounds very interesting. I would enjoy to experience it. I hope you read this HuskerOmaha since I can't spend money at this time .

Another thing to consider is that, like BHD, a lot of designers use naturally occurring sounds (like the chopper blades in BHD) or create sounds that have multiple tones, a la harmonic distortion. BHD is comprised of 6 Hz, 3HD (18 Hz), 5HD (30 Hz), etc... So, with many of them, it's impossible to notice harmonic distortion because it's masked by the tones of the effect.



If a sub produces harmonics that are still in the <20 Hz range (for example, a 5 Hz burst would have 2HD of 10 Hz and 3HD of 15 Hz, all inaudible), then yes, it would actually add to the effect, although when you are talking about tones that are below hearing, 10% or so is not that significant. So, no I don't think it makes a lot of difference unless the sub is producing very high harmonic distortion in the first 2 octaves.

kwarny - agreed that harmonic distortion is really not that noticeable. The Rythmik was at it's limits on Bass I love you but it was subtle too (maybe masked). It sounded like the surround was making a slight noise.

I am not sure if you read my post about using a computer program to test the audibility of distortion since I noticed the Submersive and CHT SS 18.1 had slightly different tones or timbre. Using the computer to simulate harmonic distortion across three octaves using different instruments and synths, it was not that obvious. The second order at -10 dBs made the sound slightly fuller (barely, I was nit picking) while the third order at -15 dBs slightly changed the timbre. These were miniscule changes. I still want to try a push pull arrangement for fun.


Just thought you might be interested in some of this stuff, and wanted to thank you for your input.

kwarny - It is very interesting. I'm glad I am young so I have plenty of years to continue learning.

I wish I had the funds to continue experimenting. If I had a room with reduced ringing and frequency response or farmland with a perfect wind block and enough pesticides or something to kill every organism that produces noise (I am just kidding PETA, only hypothetical ) with 16 Rythmiks, it would be fun to play scenes in 14 Hz extension and then engage the rumble filter (third order at 20 Hz) and compare the differences. Could have no label for the rumble filter and an independent person to flip the switches quick to make it double-blind . I doubt the government provides grants for audio research .

Maybe my reactions at the event involve the servo. I found it very articulate (time domain). Brian states that the servo allows the driver to return 3x faster than in the nonservo version. After searching for time domain I found some old posts by Brian. The ability of a driver to start is related to BL^2/Re which the servo reduces the Re by 3x. The ability to stop is related to the intrinsic q (value of the driver) which the servo reduces by 3x also. I was thinking Saturday that I wish I built another box with terminals so we could of hooked it up to a pro amp, LT it, and Eq it to fit the response of the servo version. I would add this to the list of experiments if I had 16 rythmiks to make sure that harmonic distortion would not even be considered a variable.



Bosso

Posted in bold to make it easier. I removed some of your original work as in pictures to save space. It is very interesting.

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Old 10-28-2011, 08:06 AM
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Out of curiosity I put some specLab captures of the demo scenes that your GTG used HERE .
Time stamps were included in the name description of the image in 6 digits.
I'm not sure if these captures match what you demo'ed in GTG, hope that helps

Just to be clear, I was not at the GTG (seems like you might think I was). But thanks for posting those waterfall charts. I also forgot that they (and many more) are posted at the top of the sub forum. Looks like HTTYD has some very powerful bass down low.

HuskerOmaha and crew, great job at the GTG! I really enjoyed reading along here. Always good to hear from the experts on the subject too, Mark, bossobass, etc.
I have to agree with the sealed sub route especially if you can afford to have multiples. Personally I have always preffered quality units like the SubM for music inparticular, and if possible it is always better to have more capability across frequency band. That said, as others have pointed out that is not always possible because of space, money, or both. There obviously is a place for both designs in this great hobby of ours. In my room the SubM and the Cap sound great for all these movie clips used here (I just purchased that Demo disk referred to earlier in the original thread.) Like quite a few rooms, mine eats up the bass pretty good, requiring two to energize the room properly. I have found two Caps works best as far as tactile feel, pressure, and quality of sound at all seating postions. Wish I had another SubM to test too, as I am sure that would sound great as well.

Even though I prefer the sealed sub option if possible, the Caps are very special, I actually like them just as much as the SubM for music, and in the 15Hz tune I can push them as far as my mains can go and it just keeps going, slamming me and my room like I have never experienced. Which brings me to a question that i am sure was answered, I am curious why you guys did not try the 15Hz tune in your tests. Personally I find it sounding and feeling much better than when in the 20Hz tune with clips like Cloverfield, HTTYD, etc. Sure it does not get down to 10Hz and below, but it does make a difference. I know many Cap owners prefer the 20Hz tune as I once did, but I am pretty sure in my case that was because I did not properly level match when comparing the two tunes. There is about a 2dB difference between the two above 20Hz (the 20Hz tune is louder). That and the fact that the difference is more noticeable with movies like HTTYD and Cloverfield (15hz tune reproduces more of the LFE available.)
Btw, I was very surprised that I could not detect any port noise with one port plugged hitting 118dB peaks with these bass heavy tracks! In the beginning I think I tried to convince myself I could hear some when I first got them. But after going over that demo disk again and again in the past couple of days, I just can't detect any. Which is pretty odd, it seems like it should be way under ported. Only thing I can think of is I can't push them to their limits because my mains can't go any louder.

Again, great job folks on the GTG and thanks for sharing!
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Old 10-28-2011, 08:14 AM
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Where are the ratings for the quad sealed dual opposed mfw's. I see the f20 and cap...just curious as to what it is.
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Old 10-28-2011, 08:31 AM
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Originally Posted by Mpray1983 View Post

Where are the ratings for the quad sealed dual opposed mfw's. I see the f20 and cap...just curious as to what it is.

It was already around 9pm when they finished with the DTS-10 and Growler. I left at about 8:40 and wasn't able to measure or EQ. They did hook them up, but one of the wires had come loose on a driver so one pair wasn't working. They didn't end up scoring them.

I just e-mailed HuskerOmaha and want to get these going and maybe we can write an addendum. We could use the same playlist and even compare to his dual CHT 18.1s. We have one of the modded amps from Kevin (Sandbagger) at Motor City Custom Audio for these too and need to send it back soon.
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Old 10-28-2011, 08:35 AM
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Originally Posted by desertdome View Post

It was already around 9pm when they finished with the DTS-10 and Growler. I left at about 8:40 and wasn't able to measure or EQ. They did hook them up, but one of the wires had come loose on a driver so one pair wasn't working. They didn't end up scoring them.

I just e-mailed HuskerOmaha and want to get these going and maybe we can write an addendum. We could use the same playlist and even compare to his dual CHT 18.1s. We have one of the modded amps from Kevin (Sandbagger) at Motor City Custom Audio for these too and need to send it back soon.

When I first built mine I had a similar problem with the wires coming loose. Now I always use the solderless nylon terminal connectors and they work great.

I really wanted to see the dual opposed against everything else. So please do it will be interesting to see.
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Old 10-28-2011, 11:22 AM
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Originally Posted by desertdome View Post

It was already around 9pm when they finished with the DTS-10 and Growler. I left at about 8:40 and wasn't able to measure or EQ. They did hook them up, but one of the wires had come loose on a driver so one pair wasn't working. They didn't end up scoring them.

I just e-mailed HuskerOmaha and want to get these going and maybe we can write an addendum. We could use the same playlist and even compare to his dual CHT 18.1s. We have one of the modded amps from Kevin (Sandbagger) at Motor City Custom Audio for these too and need to send it back soon.

It would be cool to see some measurements and some quick listening impressions in room of the Quattro amp vs. stock SA-1000. Be sure to crank them both during the Iron Man, Jericho scene or with something like Open Range when driving all 4 woofers (2 dual opposed boxes). Since apparently there's some "discussion" elsewhere about the significance of driver orientation and the lowest frequencies, before you start maybe you could just power the left of center dual 15 box and take a quick measurement with the drivers facing forward/back vs. left/right? I expect the differences will be seen at higher frequencies, but it should be enlightening for others reading along.

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Old 10-28-2011, 11:33 AM
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But there are 987,653 members registered here. What percent of the 987,653 members who are registered here have bass capability down to 3 Hz at reference level when measaured at the LP?

Dont worry, ill get there

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Hi Kwarny,

I read your write up with a lot of interest. Great job, and thanks for that.

I was most interested in your comments because your sub had an equally flat response to 10 Hz (unfortunately, the bottom of the graph), that being the only other sub in the group besides the SM with that distinction.

Being that the SM has dual 15s and around +8dB more juice, I believe that made a significant difference in the presentation. Since SPL can easily be equalized by multiples, there should be little difference if that were the case, IMO. It would be interesting to hear about such a comparison some day using multiples of Rythmiks to get to a specific playback level.

The sub that produces ULF at reference level doesn't seem to be lasting longer... it is lasting longer.

It's simple physics. A 30 Hz sound wave (33.3 ms) decays 6 times faster than a 5 Hz sound wave (200 ms). Therefore, wherever the FR of a sub may be arbitrarily rolled off, either by design or by the limitations of its alignment, is the biggest contributor to sonic signature with playback of full BW source.

Ringing is a different phenomenon and should be fairly easily differentiated from ULF decay times because it occurs in an audible range of frequencies.

Here's a SL comparison of my sub mic'd at the listening position vs the digital feed from the player of the lightning strikes in WOTW. You can see that it's a very good reproduction of the ones and zeroes, but notice that the mic'd version decays much slower than the digital version (at the far left, lowest frequencies):


I wasn't awrae of the phenomenon until I looked closely at these graphs, otherwise I would have noted the scroll speed and the time interval to match them up against 4 Hz, and some day I will actually do this more scientifically.

With ULF (say below 15 Hz), the chair (or whatever else in the room) doesn't resonate. A chairs resonant frequency is well above 20 Hz. Contrary to the vernacular, subwoofers don't "move air". They send a pressure wave outward using the air as a medium. The air molecules compress and then expand as the wave moves through it. If this pressure wave is strong enough, it can cause the walls, floor, chair, etc., to 'move' in reaction to the pressure wave. This can definitely be felt and is different from the same effect caused by a much higher frequency (say 40 Hz) sound wave. 'Vibration' is probably a better word to describe the effect of a higher frequency effect, added to the fact that the higher frequency effect is audible and the ULF is not.

I agree that BHD is less effective. That's because it's ULF (6 Hz and 18 Hz) are a constant tone. What many new sound designers seem to have discovered is that ULF is much more effective in pulses and bursts. Star Trek uses this effect very effectively and the pulses and the subsequent room reaction are unmistakably present, whereas the constant drone of a ULF frequency is a completely, and as you put it, more subtle effect.

Star Trek; Romulun ship emerges from the black hole in Ch 1:


Another thing to consider is that, like BHD, a lot of designers use naturally occurring sounds (like the chopper blades in BHD) or create sounds that have multiple tones, a la harmonic distortion. BHD is comprised of 6 Hz, 3HD (18 Hz), 5HD (30 Hz), etc... So, with many of them, it's impossible to notice harmonic distortion because it's masked by the tones of the effect.

If a sub produces harmonics that are still in the <20 Hz range (for example, a 5 Hz burst would have 2HD of 10 Hz and 3HD of 15 Hz, all inaudible), then yes, it would actually add to the effect, although when you are talking about tones that are below hearing, 10% or so is not that significant. So, no I don't think it makes a lot of difference unless the sub is producing very high harmonic distortion in the first 2 octaves.

Just thought you might be interested in some of this stuff, and wanted to thank you for your input.

Bosso

awesome post bosso, this thread is turning into one of my favorites and most informative that ive read in my short tenure

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Old 10-28-2011, 11:53 AM
 
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Originally Posted by Mark Seaton View Post

It would be cool to see some measurements and some quick listening impressions in room of the Quattro amp vs. stock SA-1000. Be sure to crank them both during the Iron Man, Jericho scene or with something like Open Range when driving all 4 woofers (2 dual opposed boxes). Since apparently there's some "discussion" elsewhere about the significance of driver orientation and the lowest frequencies, before you start maybe you could just power the left of center dual 15 box and take a quick measurement with the drivers facing forward/back vs. left/right? I expect the differences will be seen at higher frequencies, but it should be enlightening for others reading along.

+1

In reconciling the difference between the dual-opposed sealed Submersive's final curve and the dual-opposed sealed SS-18.2's curve we have attempt to explain 15-20dB below 20Hz.



The SS-18.2 was placed drivers front to back, Submersive side to side.

To rotate a sub 90° and see this happen I believe is unprecedented, I'd be glad to be corrected. This simple test with the Quattros would verify of course.

The room does have an affect of course, we see a dip around 14Hz that's been talked about; after which though, the Submersive recovers nicely to 10Hz. The SS-18.2, down 25dB here.

Falling into the noise floor is an interesting possibility, but with a 95dB sweep (adjusted down for the graphs) only a possibility when we assume the low end is rolling off to the point of dropping into the noise floor. With a 95dB sweep, a 70-75dB noise floor is pretty significant, no?

Here is a sim of the SS-18.2 that Craig posted (http://www.avsforum.com/avs-vb/showt...3#post17679723). With it are the Maelstrom and XXX for comparison. Output wise, on the low end it fairs pretty well.



But you see even if we roll off an 80Hz crossover, the response is quickly +/-3dB at 40Hz (+0/-6dB).

In the end, what was EQ'd in JRiver was probably not as significant as what would be needed to EQ flatter (and likely not known that it would be necessary to need so much correction).

Of course, this still doesn't explain the steeper than normal post-EQ and in-room 4th order slope.
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Old 10-28-2011, 11:55 AM
 
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The other side of the experiment, powering the Quattros with the modified and stock SA-1000 amp would be interesting. I believe we'd see more extension, maybe similar to the Submersive with the modified amp due to appropriate signal shaping, and with the stock SA-1000 I believe though less, we'd still see more extension than the SS-18.2's see with the same stock amp due to the MFW drivers being used vs the sim posted above for the SS-18.2's drivers.
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Old 10-28-2011, 12:17 PM
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HuskerOmaha does have dual CHT 18.1 subs with the same drivers as the 18.2 that was tested. Maybe we can take some more measurements when along with the Quattros.
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Old 10-28-2011, 12:32 PM
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I thought the Bic was placed in the same location. KCNitro placed it there first for pictures but then we had to move it for some reason. I remember placing the front of the Rythmik baffle where the front of the Bic's impression in the carpet was.

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Old 10-28-2011, 12:48 PM
 
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The Rythmik from the pictures had the same position and driver orientation (front) as the SS-18.2. Though not dual drivers, it is sealed and had a very similar response to the SubM:

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Old 10-28-2011, 01:04 PM
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Quote:
Originally Posted by kwarny View Post

I thought the Bic was placed in the same location. KCNitro placed it there first for pictures but then we had to move it for some reason. I remember placing the front of the Rythmik baffle where the front of the Bic's impression in the carpet was.

Yes, the BIC was in the same location as the other subs for the measuring, EQ, and listening tests. I remember you lining up the Rythmik with the carpet mark. I also had to use the BIC for the keyboard/mouse since my Bluetooth keyboard decided to quit working right before we got started.
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